Sharia Law in the UK is civil law and legally cannot supercede English law. And it was piloted in just 5 English cities and dosent exist anywhere else in England. Or Scotland, Wales or NI.
As to us being dead, dont believe the hype. 96% of the UK is NOT muslim, the current govt has restricted Muslim immigration. And Muslims hold no major political or social power. And the current govt has started a programme to enforce assimiliation via language and education.